/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.euphoria.core.client.functional;



import com.bff.gaia.unified.sdk.extensions.euphoria.core.annotation.audience.Audience;

import com.bff.gaia.unified.sdk.extensions.euphoria.core.client.io.Collector;



import java.util.stream.Stream;



/**

 * Reduce function reducing iterable of elements into multiple elements (of possibly different

 * type).

 */

@Audience(Audience.Type.CLIENT)

@FunctionalInterface

public interface ReduceFunctor<InputT, OutputT> extends UnaryFunctor<Stream<InputT>, OutputT> {



  /**

   * Create reduce functor from combinable function.

   *

   * @param combinableFunction combinable function

   * @param <V> value type

   * @return reduce functor

   */

  static <V> ReduceFunctor<V, V> of(CombinableReduceFunction<V> combinableFunction) {



    return new ReduceFunctor<V, V>() {



      @Override

      public boolean isCombinable() {

        return true;

      }



      @Override

      public void apply(Stream<V> elem, Collector<V> context) {

        context.collect(combinableFunction.apply(elem));

      }

    };

  }



  /**

   * Is this a commutative associative function with single final output?

   *

   * @return {@code true} if this is combinable function. NOTE: user code should not need to

   *     override this

   */

  default boolean isCombinable() {

    return false;

  }

}